To standardize the maximal static force (Fo) of the arm flexors, the accuracy of an anthropometric method for estimating the mid-arm cross-sectional muscle and bone area (MBA) was investigated. This was done by comparing the anthropometrically determined area (MBA.A) with the area measured by means of computerized tomography (MBA.S). In the same way, the accuracy of Heymsfield's equations (Heymsfield et al., 1982) for predicting MBA (MBA.H) from anthropometric measures was tested. MBA.A was significantly larger than MBA.S, the relative difference increasing with the thickness of the subcutaneous fat layer. This difference was attributed to a 27% underestimation of the fat layer thickness as measured with the skinfold caliper. Women being fatter than men, this caused the standardized maximal static force (Fo/MBA) to be lower in women than in men. MBA.H was 12% smaller than MBA.S. This may have been due to a difference in the way of measuring the arm circumference between the present authors and Heymsfield et al.

The force-velocity curve (FVC) of arm flexion was established in 123 untrained males and 110 untrained females aged from 15 to 36 years, and 48 arm-trained athletes competing in different sport disciplines. The FVC was described by Hill's equation and defined by the parameters: maximal static moment (M0), maximal angular velocity (omega 0), maximal power (P0) and the concavity of the FVC (H). Within the given age range the level of the curve parameters of both untrained men and women was independent of age. On average, H was the same in all three groups. As compared to M0 of the untrained males, M0 of the athletes was 33% higher and M0 of the females was 38% lower; with regard to P0 these differences were +30% and -43% respectively. omega 0 was the same for trained and untrained males, whereas omega 0 of the women was 10% lower than omega 0 of the men.

The aim of this study was to investigate the influence of specific types of muscle training, performed by previously well-trained competitive athletes, on the force-velocity relationship of the arm flexors. Four rowers, five athletes competing in tug-of-war, and six middle- and long-distance runners were measured at different stages of their training program during the period of 1 training year. The runners performed no special arm training and were included for comparative purposes. A record was made of the type and intensity of training. The force-velocity curve (FVC) was established by measuring the torques (M) and corresponding angular velocities (omega) of maximal arm flexions against different constant torques. Using Hill's equation: (M + a) (omega + b) = constant, a best fitting curve was calculated through the points of measurement. Two-way analysis of variance revealed only few statistically significant (P less than 0.05) changes in the parameters describing the course of the FVC. The results suggest that the force-velocity characteristics of muscle of previously well-trained sportsmen can hardly be influenced.

Twenty-nine boys about 16 years old were divided into a training group and a control group. The training group exercised the arm flexors in a static strength training program with 90% of the maximal static strength during 9 weeks, three times a week. Before and after the training period, the force-velocity relationship of the arm flexors was established. For this purpose the maximal speed of flexion against different but constant loads was measured. A best fitting curve was computed according to Hill's equation: (F+a) (v+b) = C. The mean maximal static strength of the training group increased from 238 N to 270 N. No change occurred in the maximal speed at low forces but the speed increased at high forces. This resulted in a more concave course of the F-v curve. Maximal power did not change significantly. No significant changes were observed in the control group.

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